Persistence of perennial ryegrass, tall fescue and cocksfoot following repeated annual sowings: influence of pasture age, grass species and cultivar in Canterbury

Abstract

Persistence is an important determinant of sown perennial pasture-grass productivity. Defining traits that affect persistence is essential for improving pasture longevity through plant breeding and identifying criteria for inclusion in cultivar ranking indices (Forage Value Index). A repeated sowings experiment commenced in 2015 under continuous sheep grazing in Canterbury. Eight cultivars of perennial ryegrass representing different ploidy, heading date, and decade of cultivar release, and one cultivar each of tall fescue and cocksfoot were sown in autumn in each year for 10 years. This
paper compares persistence trait data from a single sampling point (autumn 2025). Pasture age influenced production and composition more than grass cultivar. Peak yields occurred in 4- and 8-year-old pastures (~3430 kg DM/ha) and the lowest in 10-year old pasture (2494 kg DM/ha). Sown grass proportion dropped from 65% at establishment to around 50% in older stands. Persistence was strongly species dependent. Cocksfoot (cv. Savvy) showed the strongest persistence traits: highest sown grass proportion (61%), lowest unsown species (9%) and highest persistence score (8.2). Perennial ryegrass cultivars generally showed moderate and similar persistence, while tall fescue (cv. Hummer) performed poorly (27% sown grass, lowest tiller density and low persistence score). Persistence is an outcome driven by species morphology, establishment success, compatibility with regional soil and climatic conditions and regime of grazing management. This study reinforces the suitability of cocksfoot for long-term persistence on stony Canterbury soils, demonstrates autumn-sowing and relatively hard continuous grazing is detrimental to tall fescue persistence, while perennial ryegrass cultivars generally showed moderate and similar persistence.